The present invention relates generally to flow regulation apparatus, and more particularly, to a valve assembly adapted to permit substantially free flow through the valve in a first direction, while preventing flow through the valve in a second, opposite direction. Even more particularly, the present invention relates to valves commonly known as the "duck-bill" type.
Duck-bill valves have been known for some time and have been used in a variety of applications, several examples being shown in U.S. Pat. Nos. 3,822,720 and 3,901,272. Such a valve typically includes a housing into which is mounted a resilient flow regulator member having as its primary operative components a pair of lips arranged in a converging relationship from an open end to a normally closed end. At the normally closed end of the regulator, the lips are located adjacent each other so as to define a normally closed slit therebetween. The regulator is mounted within the housing in a sealed relationship so that flow through the housing must pass through the regulator as well. In a first or forward direction, flow enters the housing and passes into the regulator through the open end, moving toward the normally closed end. The flow pressure against the resilient lips opens the slit, allowing the flow to pass out of the regulator and the housing. When flow enters the housing from a second or reverse direction, however, flow contacts the regulator at its normally closed end, with the flow pressure against the resilient lips holding the slit in its closed position, thereby preventing flow through the valve assembly.
One application for a valve of this type is as part of a medical solution administration set. Such a set is used to deliver fluids such as plasma, medicines, and the like from a fluid supply source, such as a bottle or bag, intraveneously to a patient. A typical administration set is shown in the accompanying drawings as FIG. 1.
A fluid supply 10 is coupled by connector 12 to a drip chamber 14. Fluid then passes through duck-bill check valve assembly 16 and to one leg of a Y-site 18. The fluid next passes through an adjustable clamp 20, a filter and manual pump device 22, a second Y-site 24, and a second filter and manual pump device 26. An adapter 28 is provided at the lower end of the fluid path for connection to a needle (not shown) which is inserted into a vein of the patient.
The valve assembly 16 is placed within the fluid path so that downward flow through valve assembly 16 is in the forward direction of the valve, thereby permitting fluid to flow downwardly from supply 10 to the patient.
Occasionally, it will be necessary to provide the patient with medicine or some fluid other than that provided from supply 10. To avoid having to disconnect supply 10 from the administration set, and to provide a continuous flow of fluid to the patient, the second fluid is introduced to the administration set through filter, manual pump and adapter device 30 at Y-site 18. The second fluid supply source (not shown) is suspended at an elevation higher than supply 10. Fluid from the second source thus is at a greater fluid pressure than that from supply 10, and the second fluid displaces the first fluid at Y-site 18 and flows downwardly to the patient. Fluid from the second source will also travel upwardly toward source 10 from Y-site 18, but will be prevented from contaminating the first fluid through the action of valve assembly 16.
Whenever fluid flow is commenced through the administration set, such as when it is initially connected to fluid source 10, air bubbles typically collect around valve assembly 16. Once fluid flow is established, these bubbles must be carried away with the fluid flow, so that they will not obstruct or interfere with the smooth flow of fluid through the administration set at a constant rate.
When a duck-bill valve of the type known heretofore is used, it is necessary to dislodge the bubbles from the valve assembly 16 for them to be carried away by the fluid stream. This requires initially grasping the valve assembly 16 and/or adjacent tubing, and inverting the valve assembly 16 as shown in FIG. 2. Then, housing 32 of valve assembly 16 must be tapped or struck with a finger such as shown in FIG. 3. This frees the air bubbles which have collected in the vicinity of the regulator 34 within housing 32, permitting bubbles to be carried away.
The use of a duck-bill valve in a solution administration set is quite desirable in that the valve can be inexpensively and simply manufactured, while providing very reliable performance in service. Nonetheless, the need to invert and tap the valve assembly 16 to remove air bubbles represents a significant drawback to the use of this type of valve. Not only does the inversion and tapping represent an inconvenience to the user, but more importantly, it requires a time period of approximately 24 seconds for the air bubbles to clear from the vicinity of valve assembly 16. Further, since the removal of the air bubbles requires affirmative steps on the part of the user, the possibility is raised that such steps could be inadvertently omitted, with possible adverse effects for the patient.
What is needed, therefore, is a valve assembly of the duck-bill type which provides for removal of trapped air bubbles from the valve vicinity without the need for affirmative action on the part of the user. In addition, such a valve should enable such bubbles to be removed within a time period significantly shorter than the approximately 24 seconds required for the typical valve assembly now in use. Such a valve assembly should nonetheless retain the simplicity and inexpensiveness of construction possessed by presently known valve assemblies of this type.